Method for individually replacing ozone generator electrode assemblies

ABSTRACT

A method of replacing an electrode assembly of an ozone generator includes removing an upper closure plate of the ozone generator, removing a contact plate, lifting an individual electrode assembly to be replaced from its associated dielectric tube, and sliding a replacement electrode assembly into place. A method of replacing a dielectric tube of an ozone generator includes removing the upper closure plate, contact plate, individual electrode assembly to be replaced from its associated dielectric tube, removing a suspension means and its associated suspended dielectric tube from its respective lower seal plate aperture, sliding a replacement dielectric tube into the removed suspension means, sliding the removed suspension means and replacement dielectric tube into its respective lower seal plate aperture, sliding the lifted electrode assembly into the replaced dielectric tube, and sliding the electrode assembly with its replaced dielectric tube suspended from its associated suspension means into place.

RELATED APPLICATION DATA

The present application is a divisional of U.S. patent application Ser.No. 13/667,635 filed Nov. 2, 2012, entitled “Integrated Ozone GeneratorSystem With Removable Contact Plate And Method for IndividuallyReplacing Electrode Assemblies of Such System,” which is a CIP of U.S.patent application Ser. No. 12/806,778 filed Aug. 20, 2010 (now U.S.Pat. No. 8,372,345 issued Feb. 12, 2013), entitled “Improved IntegratedOzone Generator System.” Both are herein incorporated by reference as iffully set forth in their entirety for their pertinent and supportiveteachings.

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/274,815, filed Aug. 21, 2009, by the sameinventor/applicant, entitled “Improved Integrated Ozone GeneratorSystem.”

FIELD OF THE INVENTION

The present invention generally relates to systems for generating anddispensing ozone, and in its preferred embodiments more specificallyrelates to improvements in the physical design of ozone generatingsystems for producing ozone in a corona discharge field, and tofunctional improvements in such systems.

BACKGROUND

It has long been known that ozone is a very powerful oxidizer, and ozoneis employed in a variety of processes for a variety of purposes. One ofthe most significant of those purposes is treatment of water, both inprocesses for production of potable water and in processes for thetreatment of waste water. Ozone is effective as a water treatment agentfor the reduction of BOD and COD, VOC's, and bacterial and viralpathogens, and is also beneficial in the removal of small particles andmetal compounds. For a variety of reasons, including the fact that ozonecan be efficiently generated at the treatment site, requiring onlyelectricity and dry air, it is rapidly becoming the preferred watertreatment agent for use at remote sites and/or in undeveloped regions.Ozone is also increasingly being used in established treatmentfacilities as a replacement for chlorine.

The majority of the ozone used in water treatment facilities isgenerated in what are referred to as corona discharge generators, inwhich dry oxygen is passed through a corona discharge field created byimposing a high voltage electrical potential on a conductive electrodethat is disposed in proximity to a dielectric material imposed betweenthe electrode and an electrical ground. Most commonly, dried air is thefeedstock to the generator and ozone is created from the oxygencomponent of the air. Dried gas mixtures containing higherconcentrations of oxygen, up to and including pure oxygen, may certainlybe used, but the additional cost and complexity of that approach isusually not justified by the higher ozone output that can be achieved.For purposes of this application, the feedstock gas is referred to asair, and it is to be understood that other oxygen containing gasmixtures, or pure oxygen, could be used within the scope of thedescribed invention. The high electrical potential difference allows acorona discharge field to form between the electrode and dielectric. Asair is passed through that field, some of the molecular diatomic oxygen(O₂) is ionized, and some of the ions recombine in triplets as ozone(O₃). Most high capacity ozone generators are of the Kerag type, inwhich ozone is generated in a plurality of ozone generating cells thatare contained within a generator enclosure. Each ozone generating cellcomprises, typically, an elongate electrode that is suspended within theinterior of, but not in contact with, an elongate hollow dielectrictube, typically of glass or ceramic. In ozone generators of the priorart, the dielectric tubes are supported at their upper, open ends, by asupport plate or seal plate, with each dielectric tube extending throughan aperture in the plate downward into a container of water. The wateris used for cooling as well as being a grounded electrical conductor. Inthe prior art generators, each electrode is supported at its upper endby an electrode support plate which, like the dielectric tube supportplate, is penetrated by a plurality of apertures in which the electrodesare positioned to extend through a lower chamber lying between those twosupporting plates. Commonly, each electrode includes a fuse that extendsupwardly from the electrode to an electrical contact plate through anupper chamber lying between the electrode support plate and the contactplate. Air is drawn into the upper chamber, into the interior of theelectrodes, down the electrodes to their open bottoms, into the spacebetween the electrode and dielectric tubes, up through the coronadischarge field to produce ozone, and out the open upper end of thedielectric tubes into the lower chamber, from which the mixed air andozone is withdrawn for use.

Corona discharge ozone generators of the prior art are effective atproducing ozone, and are fairly reliable. However, the ozone generatingprocess is a high energy process, and the high energy corona dischargefield maintained within each ozone generating cell can have destructiveeffects on the generating cell components, requiring generating cellmaintenance and occasional replacement. In an ozone generator of theprior art, any maintenance activity that requires access to one or moreof the dielectric tubes requires an almost complete disassembly of thegenerator. An upper closure plate must first be removed, then theelectrical contact plate, and then the electrode support plate and allelectrodes supported from it, before the upper ends of the dielectrictubes are exposed. During the procedure of removing the electrodesupport plate and electrodes, and the reverse process of reinstallingthem, the risk of damage to electrodes and dielectric tubes is high.

Operational failure of one or more ozone generating cells within anozone generator of the prior art can also present significant problemsin addition to the difficult and time consuming procedure necessary togain full access to the cells. In the event of a cell failure arisingfrom a dielectric tube fracture, cooling water will immediately enterthe tube, electrically short the electrode to ground, and cause the fuseconnecting the electrode to the high voltage source to fail. A moresignificant problem associated with a tube fracture, however, is thepotential for flooding of the lower chamber to which all dielectrictubes of the generator open. Water entering that chamber will flood intoall dielectric tubes and bring about a catastrophic, cascading failureof all generating cells.

A similar problem can result in the event of a back flow of water fromdownstream in the treatment system of which the generator is a part. Ina back flow situation, water will back up in the conduit carrying ozoneto distribution, and into the lower chamber of the ozone generator, towhich all dielectric tubes open. Water that enters that chamber willflow into all of the dielectric tubes and precipitate a complete failureof the entire ozone generator system by shorting all of the electrodes.

The problems and increased risk of failure associated with ozonegenerating systems of the prior art have not been effectively addressed,and contribute to reluctance to utilize ozone in water treatmentoperations, especially in circumstances in which generator failures cancause extended down time in the functioning of the treatment facility.There remains a need for an ozone generator system that avoids thedisadvantages of the prior art and provides a much more reliable sourceof ozone.

SUMMARY OF THE INVENTION

The present invention provides an ozone generating system and methodsthat addresses the disadvantages of the prior art. The system orapparatus for generating ozone from an oxygen containing gas includes abase container body having a hollow interior for cooling water.

The apparatus further includes a head assembly with connection means forconnecting the head assembly to the container body. The head assemblyalso has an upper closure plate configured and dimensioned to bereceived upon the upper edge of the head assembly to enclose the system,a generally annular ledge extending from the inner surface of theassembly into the interior of the head assembly; a support ring formedof an electrically insulating material, disposed upon the annular ledgein air and water tight relationship therewith; and a removable contactplate, formed of an electrically conductive material, disposed adjacentthe support ring in air and water tight relation therewith such that anupper chamber is formed within the head assembly between the upperclosure plate and the contact plate, the contact plate penetrated by aplurality of apertures extending therethrough. The head assembly alsohas a lower seal plate connected at the lower edge of the head assemblysuch that a lower chamber is formed within the head assembly between theremovable contact plate and the seal plate, the seal plate penetrated bya plurality of apertures extending therethrough, the number of the sealplate apertures being equal to the number of the removable contact plateapertures, with each of the seal plate apertures being coaxially alignedwith a distinct one of the contact plate apertures.

The apparatus also includes a plurality of ozone generating cells equalin number to the number of the coaxially aligned apertures formed in theremovable contact plate and in the seal plate, respectively.

Each of the ozone generating cells includes suspension means disposedbetween the removable conductive contact plate and the seal plate in thelower chamber, each of the suspension means are connected at the lowerend thereof to the seal plate in air tight and water tight relation inone of the seal plate apertures and extending the majority of thedistance from the seal plate upward toward the removable contact platewithin the lower chamber, and each suspension means having a hollowinterior open at the lower end and open at the upper end.

Each of the ozone generating cells further includes (i) a hollowdielectric tube with an open upper end and a closed lower end, each ofthe hollow dielectric tubes suspended within one of the suspension meanswith the hollow dielectric tube extending through the suspension meansand supported thereby with the upper end of the dielectric tube withinthe suspension means and in gas flow communication with the lowerchamber; and (ii) an electrode assembly having an elongate hollowelectrode tube formed of an electrically conductive material, with anopen upper end thereof in electrical contact with the conductive contactplate and an open lower end, wherein the electrode tube is disposedwithin the hollow interior of the suspension means and connecteddielectric tube with the upper end of the electrode tube in gas flowcommunication with the upper chamber of the head assembly but not in gasflow communication with the lower chamber, such that a gas flowpassageway is established from the upper chamber, through the hollowelectrode tube, into the space between the electrode tube and the hollowdielectric tube wherein ozone is generated from the incoming oxygencontaining gas, and up the hollow dielectric tube exterior to theelectrode tube and into the lower chamber. As a result, each of thedielectric tubes and electrode tubes are independently accessible andreplaceable without requiring complete removal of other dielectric tubesand/or electrode tubes. The preferred structure and features of thegenerator system and the steps of the methods of the present inventionwill be described below with reference to the accompanying drawingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away side elevation view of a preferred embodiment ofthe apparatus of the ozone generating system of the invention, showingthe integration of components in a single enclosure.

FIG. 2 is a front elevation view of the system enclosure of FIG. 1.

FIG. 3 is a cut-away rear elevation view of the embodiment of FIG. 1.

FIG. 4 is a partially cut-away top plan view of the system apparatus asin FIG. 1, illustrating an array of ozone generating cells of the ozonegenerator component.

FIG. 5 is a side elevation isometric view of the ozone generator of theinvention, with water seal assembly, weir assembly, and pressure reliefvalve, shown in a full visibility view.

FIG. 6 is a cut-away side elevation view of the upper portion of thepreferred embodiment of the ozone generator of the invention and of thehead assembly.

FIG. 7a is a cut-away side elevation view of a portion of the headassembly as shown in FIG. 6, providing greater detail of the structureof the illustrated components.

FIG. 7b is a cut-away side elevation view of a contact plate formed ofan electrically conductive material, providing greater detail of thestructure of the illustrated components.

FIG. 8 is a longitudinally separated partial side elevation view of apreferred embodiment of an ozone generating cell, showing details of theelectrode assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principles of the presented embodiments and their advantages arebest understood by referring to FIGS. 1-8.

As depicted in FIGS. 1-4, the preferred embodiments the ozone generatingsystem of the invention may include an ozone generator assembly 10 thatis combined, as a packaged unit, with an incoming air inlet and filterassembly unit 12; a transformer, electrical power conditioning, andcontrol assembly 13; a cooling fan unit 14; and an ozone outlet 87, alldisposed within an enclosure or cabinet 15 that surrounds and protectsthe system components while providing easy access to them forinspection, maintenance, and the like.

The principal component in the ozone generating system of the inventionis the ozone generator assembly 10, in which ozone is produced bypassing dry oxygen or a mix of oxygen with other gases through a coronadischarge. Typically, the feedstock gas is dried air, but references to“air” in this description shall be taken to include pure oxygen or anoxygen containing gas mixture. Generator assembly 10 comprises acontainer body 16, preferably formed as a cylindrical container with aside wall 17, which has an upper edge 18, and a closed bottom 19. Adrain aperture 20, which is in indirect liquid flow communication withthe interior of the container body, is disposed in the generatorassembly at an elevation between the elevation of bottom 19 and theelevation of upper edge 18 of the container body.

The generator assembly 10 also includes a head assembly 21, preferablyalso cylindrical like the container body but of slightly largerdiameter, coaxially aligned with and releasably connected to thecontainer body 16 so that the lower edge 22 of the head assembly 21 isreceived against the upper edge 18 of the container body 16 in closelyfitting relation to form a water tight seal. In one embodiment, theupper edge 18 of the container body and lower edge 22 of the headassembly are releasably connected with mating flanges connected bybolts, and in the drawing figures the reference numbers 18 and 22identify annular flanges around the top of the container body 16 and thebottom of the head assembly 21. However, the specific manner ofconnection of the head assembly to the container body is not asignificant feature of the invention, and any effective manner ofreleasably connecting those components may be used.

As depicted in FIG. 6, head assembly 21 includes an upper, air chamber23 and a lower, ozone chamber 24 immediately below the air chamber, bothsurrounded by a head assembly side wall 25. An upper closure plate 26extends across the upper edge 27 of the head assembly side wall 25, andis preferably releasably connected thereto, so that the upper closureplate 26 may be removed to provide access to the interior of the headassembly 21 without removing the head assembly 21 from the containerbody 16. Again, it is contemplated that upper edge 27 of side wall 25will be formed as an annular flange to which the outer perimeter of theupper closure plate 26 is connected, but any effective manner ofconnection may be used. Intermediate the upper and lower edges of sidewall 25, an annular ledge 28 extends from the inner surface of side wall25 inwardly a sufficient distance to provide a stable support for acontact plate support ring 29 at the transition between the upper andlower chambers of the head assembly 21.

As depicted in FIG. 7a , contact plate support ring 29 is an annularring with an outer edge 30 at the perimeter of the support ring 29, andan inner edge 31. In one illustrative embodiment of ring 29, a notch isformed around the support ring 29 at the intersection of edge 30 and thelower surface 32 of the ring, providing a head assembly ledge 33 to bereceived upon ledge 28 so as to suspend the contact plate support ring29 in the interior of the head assembly 21. Similarly, a notch is formedin the inner edge 31 of contact plate support ring 29 at theintersection of that inner edge 31 with ring upper surface 34, providingan annular ledge 35 extending around the inner edge 31 of contact platesupport ring 29. Contact plate support ring 29 is formed of aninsulating material, preferably but not limited to ceramic or plastic,to electrically isolate components that are in direct contact with thesupport ring 29 but not in contact with each other. Further, contactplate support ring 29 is sealed against ledge 28 by, preferably, O-ringgasket 36 extending fully around the intersection between ledge 33 ofthe ring 29 and ledge 28 of the head assembly 21 to form an air tightand water tight seal. The connection of contact plate support ring 29 tohead assembly ledge 28 may be made by any convenient conventional means.Contact plate support ring 29 may be formed as a continuous body, or maybe divided into two or more segments, if desired. A contact plate 37,configured and dimensioned so that the perimeter edge portion 38 of thecontact plate 37 is received on annular ledge 35 of contact platesupport ring 29 with the contact plate 37 extending fully across andfilling the space surrounded by contact plate support ring 29. An airtight and water tight seal is formed between annular ledge 35 andcontact plate 37 by an O-ring gasket 39 extending fully around ledge 35.The connection of the contact plate 37 to the contact plate support ring29 may be made by any convenient conventional means, so long as thecomponents remain electrically isolated. The combination of ledge 28,contact plate support ring 29, and contact plate 37 defines the bottomof upper chamber 23 of the head assembly 21 and divides the upperchamber 23 from lower chamber 24. Contact plate 37 is formed of anelectrically conductive material, preferably stainless steel, andfunctions, as depicted in FIG. 7b , to electrically connect ozonegenerating cells 48, described below, to transformer assembly 14 throughhigh voltage lead 40, connected to contact plate 37 by terminal 41.

In an alternate embodiment, the relative position of the contact platesupport right and the contact plate may be switched. For example, thecontact plate support ring (now functioning as a restraining ring) has aring upper surface substantially similar in structure to the lowersurface 32 of the first embodiment and has a support ring lower surfacesubstantially similar in structure to the upper surface 34 of the firstembodiment, including having an annular notch with dimensions similar tothe annular ledge 35 of the first embodiment.

In assembling the alternate embodiment, the removable contact platewould be first positioned above the electrode insulators 65 of the ozonegenerating cells 48 and then the support ring (now functioning as arestraining ring) would be positioned above the contact plate with theperimeter edge portion 38 of the contact plate seated against theannular notch of the support plate and supported therein by the uppersurfaces 68 of the electrode insulators 65 of the ozone generatingcells, as will be described in more detail below in connection with FIG.8.

As an alternative to connecting high voltage lead 40 directly to contactplate 37, contact may be made through an electrical conductor disposedwithin support ring 29 that makes contact with the contact plate 37 whenthe contact plate 37 is connected to the support ring 29. In thisalternate embodiment an insulated channel is formed in contact platesupport ring 29 and an electrical conductor is disposed in and throughthe channel to one or more electrical contacts within, e.g., annularledge 35 formed at the inner edge of support ring 29. When the contactplate 37 is received upon annular ledge 35 and connected to support ring29, an electrical connection between the electrical conductor disposedin the support ring 29 and the contact plate 37 is established.

In this alternate embodiment, a conductor establishing contact betweensupport ring 29 and the exterior of the head assembly is disposed withinan insulated tower that extends from contact with support ring 29through either upper closure plate 26 of the head assembly 21 or throughside wall 25 in sealed relation therewith. High voltage lead 40 isconnected to the conductor at the outer end of the insulated tower.

To provide a passageway for the flow of air from the upper chamber 23 ofthe head assembly 21 to ozone generating cells 48, described below,contact plate 37 is penetrated by a plurality of apertures 42. Apertures42 are spaced through the central portion of the contact plate 37 inwardfrom the perimeter portion 38 so that none of the apertures 42 penetratethe portion of contact plate 37 that overlies annular ledge 35 ofsupport ring 29. Apertures 42 are grouped in sets, and the sets ofapertures are disposed in a selected pattern across the contact plate37.

As depicted in FIGS. 6 and 7 a, the lower end of head assembly 21,opposite upper closure plate 26, is closed by seal plate 43, whichextends fully across the lower end of the head assembly 21 between sidewall 25, adjacent to lower edge 22 of the head assembly 21, andgenerally defines the bottom of lower chamber 24 of the head assembly.Seal plate 43 may be removably connected to side wall 25, and/or loweredge 22, may be permanently connected to the sidewall and/or lower edge,or may be integrally formed with lower edge 22 as a blank flange platethat extends fully across the lower end of the head assembly 21 and isconnected to the lower end of the side wall. Although convenient,removability of the seal plate 43 is not necessary to provide access tothe internal components of the ozone generator of the present invention.The specific structure of upper and lower closures for the generatorhead assembly 21 is not critical to the invention, and variety ofdesigns in addition to those mentioned above may be used within thescope of the invention.

As depicted in FIG. 8, seal plate 43 is penetrated between upper face 44and lower face 45 by a plurality of apertures 46, disposed in a selectedpattern across the seal plate 43. The pattern of disposition ofapertures 46 is the same as the pattern of disposition of the sets ofapertures 42 in contact plate 37, so that each aperture 46 will bepositioned directly below a set of apertures 42 in the final alignmentand connection of head assembly components. Each of apertures 46 extendsinto seal plate 43 from upper face 44 the majority of the distance tolower face 45 at a first diameter, and then narrows to a second, smallerdiameter through the remainder of the distance to lower face 45, formingan annular ledge 47 at the transition between the two diameters. Thelarger diameter portion of each aperture 46 above ledge 47 is threaded.

Ozone generator assembly 10 also includes a plurality of ozonegenerating cells 48, within each of which a corona discharge is createdand ozone is generated from air that is flowing through the coronadischarge within the cell 48. Each generating cell 48 in a typicalcorona discharge type ozone generator basically comprises an electrodeand a dielectric tube within which the electrode is suspended and fromwhich the electrode is electrically separated. When a high voltagesource is connected across the electrode and the outer opposite surfaceof the dielectric tube, the high potential difference across thedielectric allows the creation of a corona discharge field between theelectrode and the inside adjacent surface of the dielectric tube. Whendry air or oxygen is passed through the corona discharge field, theincoming oxygen, which is in the O₂ molecular form, is ionized and aportion of the ions recombine as O₃, known as ozone.

As depicted in FIG. 8, each ozone generating cell 48 includes asoperational components a threaded collar insert 49, a dielectric tube50, and an electrode assembly 51. The threaded collar insert 49comprises a hollow body, with an open upper end 52 and an open lower end53. The height of threaded collar insert 49 between upper and lower endsis less than the height of the lower chamber 24 of the head assembly 21between contact plate 37 and seal plate 43. The edge of insert 49 atupper end 52 is preferably formed with a plurality of notches or slotsextending into the insert 49 from insert upper end 52, to provide gasoutlet passages through the wall of the insert 49 at its upper end 52and to provide a means of connecting a turning device to engage and/ordisengage the threads of threaded collar insert 49 with the threads inthe large diameter portion of apertures 46 in seal plate 43 until thelower end of the threaded collar insert 49 is received on ledge 47 nearthe lower face of the seal plate 43. An O-ring gasket 56 is disposedbetween the lower end of the threaded collar insert 49 and the ledge 47,to form a gas and liquid tight seal.

Each of dielectric tubes 50 comprises an elongate cylindrical tube withan open upper end 57 and, preferably, a closed lower end 58. It ispreferred that tubes 50 be formed of glass, but other dielectricmaterials, such as a ceramic material, may be used in combination with aconductive (e.g. metallic) sleeve around some or all of the outersurface of the dielectric tube 50. The outside diameter of dielectrictube 50, especially at its upper end 57, is slightly less than theinside diameter of the lower portion of the threaded collar insert 49,so that the upper portion of the dielectric tube 50 may be extendedfully through aperture 46 without interference, and inserted into theinterior of threaded collar insert 49 through lower end 53. As insert 49is tightened in aperture 46, O-ring 56 will expand across the spacebetween the outer surface of the dielectric tube 50 and the innersurface of the insert 49 to seal that space as well as sealing betweenthe lower end 53 of insert 49 and annular ledge 47. Alternatively, apacking ring or sleeve 59 may be disposed between the outer surface ofthe dielectric tube 50 and the inner surface of the insert 49, above thelower end of the insert 49, in addition to O-ring 56. In addition toproviding a secondary seal, the use of packing ring 59 between the tube50 and insert 49 also provides at least a mild frictional connectionbetween them.

Electrode assembly 51 comprises an elongate hollow electricallyconductive electrode tube 60, preferably metallic, with an open upperend 61 and an open lower end 62 and an elongate hollow electrodeinsulator 65 with an upper end 68 opposite lower end 66. Electrodeinsulator 60 is attached to the upper open end 61 of the electrode tube60 by means of an electrically conductive connector tube 63 (such as,for example, a bayonet tube), of smaller diameter than electrode tube60. Connection between the connector tube 63 and the electrode tube 60is made by an annular connector 64, which is disposed in, and fills, thespace between the outer surface of the connector tube 63 and the innersurface of the electrode tube 60, so that gas flowing down the connectortube 63 is allowed to flow into and down the interior of the electrodetube 60. Annular connector 64 also establishes electrical contactbetween connector tube 63 and electrode tube 60. The upper end ofconnector tube 63, which extends outwardly from annular connector 64, isattached to electrode insulator 65 by means of a bayonet pin whichinserts into a receiving groove formed inside the hollow opening ofelectrode insulator 65. Alternately, connector tube 63 may be attachedto the interior of the hollow opening of electrode insulator 65 by anyconvenient means of cross pinning or swage. All components of theelectrode assembly 51 are thus suspended from and supported by thehollow block portion 69 of the electrode insulator 65.

Electrode insulator 65 comprises an elongate hollow member with an upperend 68 opposite lower end 66. The portion of insulator 65 adjacent toupper end 68 extending downward to ledge 98 is formed as a hollowsupport block 69, which has an outside diameter generally equal to theoutside diameter of threaded collar insert 49. The lower portion of theelectrode insulator 65, from ledge 98 to lower end 66, is of a diameteradequately less in dimension to the inside dimension of the dielectrictube 60 to allow for the passage of the air or ozone containing air topass into the lower chamber 24 of head assembly 21. The configurationand dimensions of electrode assembly 51 allow for the electrode assembly51, to be inserted through threaded collar insert 49 and into theinterior of dielectric tube 50 until further movement is arrested whenledge 98 of hollow support block 69 is received on the upper end 57 ofdielectric tube 50 or alternately, the upper end 52 of threaded collarinsert 49 where the electrode assembly 51 is wholly supported andrestrained between the lower surface of contact plate 37 and the upperend 57 of dielectric tube 50, or alternately, by the upper end 52 ofthreaded collar insert 49. Under both embodiments, the order of assemblyimproves upon the prior art by providing direct access to any one of theplurality of ozone generating cells 48 by the removal of only the coverplate 26, contact plate support ring 29, and contact plate 37.

In order for an ozone generating cell 48 to operate, an electricalconnection must be established between the electrode tube 60, throughthe connector tube 63, and a high voltage source. The electrical pathmay be completed by contact spring 70 and fuse 71. Spring 70 is disposedin the interior of electrode insulator 65 with its lower end in contactwith connector tube 63, and fuse 71 may be disposed above spring 70,with the lower end 72 of the fuse in contact with spring 70 and theupper end 73 extending outwardly above support block 69.

In the ozone generator of the invention, the number of inserts 49,dielectric tubes 50, and electrode assemblies 51 is the same, and isequal to the number of apertures 46 in seal plate 43 and to the numberof sets of apertures 42 in contact plate 37. When the contact plate 37is positioned during assembly of the ozone generator, the upper edge ofhollow support blocks 69 is brought into contact with the lower surfaceof the contact plate 37 around aperture 42 and the upper end of fuse 71is brought into electrically conductive contact with the contact plate37. An O-ring gasket 74 is disposed between the upper end of supportblock 69 and the lower surface of contact plate 37 to prevent gas flowfrom apertures 42 into the lower chamber 24 of head assembly 21. Toaccommodate any dimensional variations and to assure that the electrodeinsulator and O-ring 74 remain firmly seated against the contact plate37, a wave spring 75 is disposed between the upper end of insert 49 andthe lower end of support block 69. A washer 76 may also be disposedbetween the wave spring 75 and the surface against which the springforce is applied to further seat the components.

In an assembled unit of the generator of the present invention,dielectric tubes 50, connected to seal plate 43 with threaded collarinserts 49, extend into the interior of the container body 16 where theyare surrounded by cooling water. The lower ends 58 of dielectric tubes50 may be received upon a supporting structure or pad near the bottom ofthe container base, or the tubes maybe hung freely without support, asdesired, within the scope of the invention. The cooling water in thecontainer base absorbs heat created by the corona discharge in thegenerator cells, and is continuously exchanged during operation of thegenerator to remove the excess and potentially damaging heat. Heatedwater from the generator may be circulated in a closed loop with heatexchange to cool the water before returning it to the generator, thewater may be discharged and replaced with fresh, cooler water, or acombination of those two approaches may be used. The manner in whichcooling water is used within the system of the invention is notsignificant to the scope of the invention, and will be determined byspecific conditions and water availability at each site where thegenerator system is used.

Electrode assemblies 51, which are suspended by upper edge 57 ofdielectric tubes 50, or alternately by the upper end 52 of threadedcollar inserts 49 and also supported by seal plate 43, extend frominsert 49 downward into the dielectric tubes 50, and upward through thelower, ozone chamber 24 of the head assembly 21 to make electricalcontact with contact plate 37. Contact plate 37, and the componentssupporting it in the head assembly 21, separate the upper, air chamber23 of the generator head assembly from the lower, ozone chamber 24, andit will be understood that the design of the ozone generator of thepresent invention avoids positioning any of the generator cellcomponents in the upper, air chamber 23 of the head assembly 21. It isalso to be understood, as can be seen from the drawing figures, thatinsert 49 extends upwardly above seal plate 43 through the majority ofthe height of the lower, ozone chamber 24 of the head assembly in whichit is disposed, and that the ozone containing gas exiting from thegenerator cell exits through the top of insert 49.

It will be seen and understood that the structure of the ozone generatorof the present invention eliminates the need for an electrode supportplate that, in prior art devices, divides the upper, air chamber of ahead assembly from the lower, ozone chamber of the head assembly, and towhich all electrode supports and insulators are connected. In the priordesigns the dielectric tubes are supported by a plate, similar to sealplate 43, that closes the bottom of the head assembly, and prior artelectrode assemblies are suspended from the additional electrode supportplate. The electrode assemblies extend within the dielectric tubes butremain completely physically independent of the tubes as well aselectrically isolated from them. In the structure of the ozone generatorof the present invention, each generator cell comprises an electrodeassembly and dielectric tube assembly that are physically connected butelectrically isolated from each other, and each is independent of theother cells. With the prior art designs, it is necessary to remove theelectrode support plate and all electrode assemblies, after the contactplate is removed, in order to gain access to any of the dielectrictubes. If the electrode support plate and electrodes are removedtogether, great care must be used in lifting the support plate andelectrodes so that the plate and electrodes are lifted straight up,without rotation, to avoid destroying electrodes and/or dielectrictubes. Alternatively, each electrode in a prior art device may beindividually removed from the support plate and lifted from theassociated dielectric tube before the electrode support plate is removedto provide access to the dielectric tubes. With the generator of thepresent invention, however, removal of the contact plate allows eachelectrode assembly and each dielectric tube assembly to be accessedindividually. A single electrode assembly can be easily and quicklyreplaced by removing that electrode assembly from its dielectric tube,which is accomplished by lifting the electrode insulator and suspendedelectrode from the dielectric tube, and sliding a replacement electrodeassembly into place. Similarly, each dielectric tube can be individuallyaccessed and replaced by removing the electrode assembly from that tubeand then unscrewing the insert and suspended tube from the seal plate. Anew dielectric tube and insert can be installed just as easily andquickly as the old one was removed. The improved accessibility to theozone generator components provided by the present invention will varysignificantly reduce the down time associated with generator maintenancein comparison to the prior art, with directly resulting reductions inlabor costs and lost operational time.

In the operation of the system of the invention, produced ozone will bedrawn from the generator by the suction created in an ozone distributionunit, which mixes ozone containing gas with, e.g., wastewater, in thecourse of treatment. The ozone distribution unit develops an inletsuction that reduces the pressure within the ozone generator to belowthe ambient air pressure external to the generator, and draws air intoand through the generator, along with the produced ozone. Dry air issupplied to the system apparatus from an outside source, and is drawnthrough air filter unit 12 at a controlled flow rate measured by sensorassembly 11, and into the upper chamber of the generator head assembly.In addition to the flow rate sensor, assembly 11 also preferablyincludes a dew point sensor to monitor the moisture content of the airentering the generator. From the upper chamber the dry air is drawnthrough apertures 42 in contact plate 37, into and through the hollowinterior of electrode insulator 65, and into the interior of electrodetube 60, to which a high voltage electrical potential is applied.

Electrical power requirements of the system of the invention aresatisfied by drawing upon a source of electricity outside the boundariesof the system of the invention, and utilizing transformer assembly 13 tocreate a high voltage potential difference between opposite poles. Apower conditioning unit, for smoothing variations and fluctuations inthe electrical supply, may be provided between the electrical supply andthe transformer assembly if desired or deemed appropriate. One side ofthe high voltage potential is connected to contact plate 37 through highvoltage lead 40, through any intervening conductors, and is separatedfrom ground by the air space between the electrode tubes 60 anddielectric tubes 50 and by the dielectric tube material itself. Ground,relative to the high voltage supply, is established through thegenerator body and the cooling water in the container body surroundingthe dielectric tubes. The high potential difference that exists acrossthe gap between and along the surfaces of the tubular electrode and thedielectric tube creates a corona discharge within the gap.

Air drawn into the generator cell is drawn down the interior of thetubular electrode and back up the dielectric tube between the outsidesurface of the electrode tube and the inside surface of the dielectrictube, through the corona discharge. As the air passes through the field,diatomic molecular oxygen is split into oxygen atoms and ionized. Someof the oxygen ions recombine in triplets to form ozone, and theremainder recombines into diatomic molecular oxygen. The ozonecontaining gas is drawn to the top of the dielectric tube, into thelower chamber of the head assembly through the notches or other gapsbetween the upper end of insert 49 and the lower surface of supportblock 69 of the electrode insulator, and from the lower chamber of thehead assembly through an ozone exit port 77 and through a water sealassembly 78 to the ozone distribution unit.

The use of a water seal in ozone generators is known in the prior art,but in the prior art these assemblies are separate from the ozonegenerator and may be disposed at some distance from it. In the presentinvention, water seal assembly 78 is a part of the ozone generatoritself, a unique configuration that provides certain advantages andbenefits that have not been accomplished by the prior art. In thegenerator of the invention, ozone containing gas exits from the lowerchamber of the head assembly through exit port 77, formed in headassembly side wall 25, and into a plenum 79 that is formed as a part ofthe head assembly. The specific disposition and configuration of plenum79 is not critical, but it is preferred that the bottom closure 80 ofthe plenum be in generally the same plane as seal plate 43. Bottomclosure 80 may be integral with seal plate 43, or may be a separatecomponent.

Water seal assembly 78 includes an elongate open ended outer tube 81that is connected at its upper end 82 to bottom closure 80 of plenum 79,around an aperture 83 that penetrates bottom closure 80. Tube 81 extendsdownwardly from bottom closure 80 to its lower end 84 within a drainchamber 85 disposed within, or adjacent to and in water flowcommunication with, generator container body 16. In the preferredembodiment, drain chamber 85 is formed within container body 16, eitheras an integral part or as a separate component that is connected withinthe container body. Drain aperture 20 connects directly to the interiorof drain chamber 85, rather than to the major portion of the interior ofthe container body. Drain aperture 20 is disposed and connected to drainchamber 85 above the lower end 84 of outer tube 81, so that when wateris added to the drain chamber the lower end of the outer tube will besubmerged before the water level reaches the drain aperture and isallowed to exit drain chamber 85 through that aperture. The bottom ofdrain chamber 85 is closed, either by bottom 19 of the container body ifthe chamber extends fully to the bottom of the container body, or by aseparate bottom closure, so that the only connection between theinterior of drain chamber 85 and the interior of the container body isat upper edge 86 of the drain chamber. An ozone tube 87, for conveyingozone containing gas from the ozone generator system, extends from theexterior of the generator head assembly, preferably through the topclosure, through plenum 79, and through plenum bottom closure 80 in theinterior of and in concentric, coaxial relationship with outer tube 81.Ozone tube 87 is of smaller cross-sectional dimension than outer tube81, leaving an annular space 88 between the outer surface of the ozonetube 87 and the inner surface of the outer tube 81. Ozone tube 87extends below bottom closure 80 a shorter distance than outer tube 81,so that the lower, open end 89 of ozone tube 87 is above the lower end84 of tube 81, and is also above the level of drain aperture 20.

Cooling water is preferably introduced to the interior of the containerbody through an inlet disposed near container bottom 19, and exitsthrough aperture 20 after flowing from the container body into drainchamber 85. The level of cooling water within the container body 16 iscontrolled and maintained by weir assembly 90, disposed between the maincontainer body 16 and drain chamber 85, adjacent to upper edge 86 ofthat chamber. In the preferred embodiment, drain chamber 85 and weirassembly 90, are disposed outside the interior of container body 16 andconnected to the outer surface of container body side wall 17. In thisembodiment weir assembly 90 includes a hollow weir box 91 with a closedbottom. The top of the weir box will underlie, and be effectively closedby, either flange 18 at the upper edge of the container body side wall,or flange 22, at the lower edge of the head assembly side wall,depending upon design and construction decisions that are not criticalto the scope of the invention. It is preferred that a transparent sightglass be disposed in the weir box to provide a view of the interior ofthe weir box and the level of the cooling water within the containerbody, but the sight glass could be omitted if desired. In the preferredembodiment, box 91 is connected to side wall 17 of the container body,around a substantially rectangular aperture 92 in the container bodyside wall that is open between the interior of the container body andthe interior of the weir box. The upper edge 93 of aperture 92 isdisposed below the upper edge 18 of side wall 17 a distance slightlygreater than the distance across the air space to be maintained betweenupper edge 18 and the surface of the cooling water in the containerbody. In the preferred embodiment the distance through that air space isapproximately two inches, and the upper edge 93 is disposedapproximately one-eighth inch below the cooling water surface, but otherdimensions could be used. It will be understood that weir box 91 maybeformed in various ways and still accomplish the same function. Box 91may be formed with two side walls disposed perpendicular to each other,with the outer edge of one side wall and an outer edge of the bottomclosure connected to the container body side, and with the outer edge ofthe other side wall and the other outer edge of the bottom connected tothe adjacent wall of the drain chamber. Box 91 may also be formed withthree side walls and a bottom, leaving one open side, and connected toside wall 17 by connecting the free edges of the two opposing side wallsand the free edge of the bottom to the container body side wall. In athird approach, box 91 may be formed with four connected side walls anda bottom, and connected to sidewall 17 by placing one of the weir boxside walls against the container body wall and connecting the two wallsto each other. In this alternative structure, an aperture matchingaperture 92 is formed in the weir box side wall connected to thecontainer body wall and aligned with aperture 92.

In a design in which the drain chamber is disposed within the containerbody, weir assembly 90 is also disposed with the container body, andaperture 92 is formed in one of the side walls of weir box 91 ratherthan in side wall 17 of the container body 16, since in thisconfiguration cooling water enters the weir box without passing throughthe container body side wall.

In both of these design approaches, weir assembly 90 includes a weir 94,over which water may flow from the interior of the weir box into theinterior of the drain chamber. In the illustrated embodiment, weir 94 isformed by cutting a slot in the side wall or walls separating theinterior of the weir box from the interior of the drain chamber. In aconstruction in which the weir box interior and the drain chamberinterior are separated by two walls received against and connected toeach other, the slot for weir 94 is sealed around the three edges of theslot so as to prevent water from entering any space between those walls.The upper edge 95 of weir 94 is positioned at the elevation at which thelevel of cooling water in container body 16 is to be maintained, whichis slightly above the upper edge of aperture 92. If the space betweenthe surface of the cooling water and the upper edge 18 of the containerbody side wall is approximately two inches, the upper edge 95 of weir 94is the same approximately two inches below upper edge 18, andapproximately one-eighth inch above the upper edge of aperture 92.

As the container body of the generator is filled with water and thewater level reaches the elevation of the lower edge of aperture 92,water will flow through aperture 92 and fill the weir box 91 while theremainder of the container body is filled. When the water level in theweir box reaches the upper edge 95 of weir 94, the water will begin toflow over the weir into drain chamber 85, within which the water levelwill rise until it reaches the level of drain aperture 20. Anyadditional water flowing over weir 94 into the drain chamber will drainout through aperture 20. It will be understood that, once drain chamber85 is filled, the water level in the drain chamber is independent of thewater level in container body 16, so that if the cooling water level inthe container body is allowed to drop there is no effect on the level ofwater in the drain chamber, and the flow of air and ozone through thegenerator may continue until the flow of cooling water is resumed, oruntil the generator is shut down.

Although ozone generators can operate for extended periods withrelatively few operational problems, those of the prior art, especially,can be adversely affected by problems arising from both internal causesand external causes. The two problems of most concern are the internalfailure of a generating cell, resulting from or involving fracture of adielectric tube, and an external problem with an ozone distribution unitthat causes a back flow of water into the ozone generator head assembly.

When an ozone generating cell fails, with fracture of the dielectrictube, cooling water is allowed to enter the dielectric tube and shortcircuits the associated electrode, causing the fuse that connects theelectrode to the contact plate to open and removing power from thefailed generating cell. Other generating cells that are not affected bythe initial failure and electrical short will continue to function andthe generator may continue in service if flooding of the generator headassembly can be avoided. If the suction that draws air and ozone throughthe generator is sufficiently high and the pressure within the lowerchamber of the head assembly is sufficiently below the ambient, externalpressure, cooling water that enters the fractured dielectric tube willbe drawn upward into the lower, ozone, chamber of the head assembly.From that chamber, water may flow into intact dielectric tubes of othergenerating cells through the ozone exit path, and cause an immediatefailure of each such cell. The entry of even a small amount of liquidwater or water vapor into a generating cell can cause cell failure, or,even if the dielectric tube does not fail, will cause a significantreduction in ozone production and a significant increase in the creationof very undesirable nitrogen oxides and acids.

The generator of the present invention addresses this problem in severalways. In the preferred manner of operation of the generator of theinvention, the pressure differential between the interior of the lowerchamber of the head assembly and the atmosphere around the generator isrelatively low. A pressure differential of about two inches of water ispreferred, though other values could be used. The selected pressuredifferential will be sufficient to maintain the flow of air/oxygen andozone through the generator for effective operation of the generator,and to supply ozone to meet downstream processing needs, without beingsufficiently high to draw water into the head assembly of the generatorof the invention. In the generator of the invention, the level of thecooling water in the base container is maintained at a distance belowthe bottom of the seal plate of the head assembly, and the ozone outletof each insert connected to the seal plate is disposed relatively highabove the seal plate and near the contact plate that divides the lowerchamber of the head assembly from the upper chamber. In the ozonegenerator of the invention, the pressure differential with which thegenerator operates is insufficient to draw cooling water up a dielectrictube over the distance of the gap between the cooling water level andthe outlet from the dielectric tube in almost all circumstances, and theentry of water into the lower chamber of the head assembly is veryunlikely. Even if water does enter that chamber, it would be necessaryfor the water to essentially fill the chamber before reaching the levelof the ozone outlet from the generating cells and entering thedielectric tubes. As an additional measure to prevent cooling water frombeing drawn into the head assembly, the generator of the inventionfurther includes a pressure relief valve 96, disposed in an aperture 97that forms a gas flow passageway between the lower chamber of the headassembly and the water seal drain chamber or the container body belowthe seal plate. If the pressure differential between the lower chamberof the head assembly and the interior of the container body, which is incommunication with and thus at the same pressure as the drain chamber,exceeds the threshold pressure for the pressure relief valve, the valvewill open and the pressure differential between the two spaces will bereduced. When the pressure differential is reduced to below the pressurerelief valve threshold value, the valve will close. The pressure reliefvalve will maintain the pressure differential within a selected rangethat is sufficient to draw gas through the generator, but not so high asto draw cooling water into the lower chamber of the head assembly.

Flooding of the generating cells can also occur in the event of a backflow of water from an ozone distribution unit because of problemsdownstream from the ozone generator. In ozone generator designs of theprior art, ozone is drawn directly from the lower chamber of thegenerator head assembly, typically through an outlet port in the sidewall of the head assembly, and any back flow of water from downstreamenters directly into that chamber. Water under sufficient back flowpressure to enter the generator head assembly will almost certainlyflood that chamber and flow, more or less simultaneously, into alldielectric tubes in the generator and precipitate a catastrophicgenerator failure.

During normal operation of the generator, the suction produced by thedownstream ozone distribution unit draws the ozone produced in thegenerating cells into the lower chamber of the head assembly, throughaperture 83 in plenum bottom closure 80 through the interior of outertube 81, into the lower end of ozone tube 87, and through that tube tothe distribution unit. In the event of a downstream upset that forceswater to flow back upstream to the ozone generator, the back flow waterwill enter the generator through ozone tube 87 and be released from thelower end 89 of the ozone tube. If the conduit carrying ozone from thegenerator were connected directly to the lower chamber of the headassembly, water back flow to the generator would, as noted above, beforced directly into that lower chamber. In the ozone generator of theinvention, however, water back flowing from downstream into theintegrated generator system will be confined within ozone tube 87 as itpasses through the ozone generator head assembly, and none of the waterwill be released into the head assembly. Instead, the water will bereleased from the lower end of ozone tube 87 into outer tube 81, fromwhich it flows from the open bottom of tube 81 into drain chamber 85,from which it then exits the generator structure through drain aperture20. Because water back flowing into the ozone generator passes throughthe water seal assembly only, and not into any portion of the generatorhead assembly or container body outside the drain chamber, the onlyeffect on the generator of the invention is a cessation of ozoneproduction. No damage will be done to the ozone generator, and thegenerator can be returned to service immediately when the downstreamproblem causing the back flow is corrected, saving both generator repairor replacement cost and processing time that would otherwise be lost.Integration of the water seal structure with the generator in the sameenclosure facilitates monitoring and coordinated control of the ozonegenerator and the protective flow control systems to a degree notavailable in the prior art.

The foregoing description of the ozone generator system of the inventionis intended to be illustrative and not limiting. It is contemplated thatothers of skill in the art may devise additional alternative embodimentsand variations on the basis of that illustrative disclosure, all withinthe scope of the invention in accordance with the following claims.

What is claimed is:
 1. A method of replacing an electrode assembly of anozone generator having a head assembly with a side wall, a removableupper closure plate and a lower seal plate, and a removable conductivecontact plate disposed intermediate the upper closure plate and lowerseal plate for forming upper and lower chambers therein, wherein thecontact plate and lower seal plate have a plurality of coaxially alignedapertures formed therein for suspending a plurality of ozone generatingcells, each ozone generating cell including removable suspension means,a hollow dielectric tube suspended from and extending through itsrespective removable suspension means, and an electrode assemblysuspended within the hollow interior of its respective dielectric tubethe method comprising: removing the upper closure plate; removing thecontact plate whereby each of the individual electrode assemblies may beindividually accessed; lifting the individual electrode assembly to bereplaced from its dielectric tube; and sliding a replacement electrodeassembly into place.
 2. The method of claim 1, wherein: sliding areplacement electrode assembly into place comprises inserting theelectrode assembly through it associated suspension means and into theinterior of its associated dielectric tube until further movement isarrested responsive to the upper end of the dielectric tube receivingthe electrode assembly.
 3. The method of claim 1, wherein: sliding areplacement electrode assembly into place comprises inserting theelectrode assembly through it associated suspension means and into theinterior of its associated dielectric tube until further movement isarrested responsive to the upper end of the suspension means receivingthe electrode assembly.
 4. The method of claim 1, wherein: eachelectrode assembly comprises an electrode insulator comprising anelongate hollow member wherein lifting the individual electrode assemblyfrom its dielectric tube comprises lifting the electrode insulator. 5.The method of claim 1, wherein: each electrode assembly comprises anelectrode insulator comprising an elongate hollow member; and sliding areplacement electrode assembly into place comprises inserting theelectrode assembly through it associated suspension means and into theinterior of its associated dielectric tube until further movement isarrested responsive to the upper end of the dielectric tube receivingthe electrode insulator.
 6. The method of claim 1, wherein: eachelectrode assembly comprises an electrode insulator comprising anelongate hollow member; and sliding a replacement electrode assemblyinto place comprises inserting the electrode assembly through itassociated suspension means and into the interior of its associateddielectric tube until further movement is arrested responsive to theupper end of the suspension means receiving the electrode insulator. 7.A method of replacing a dielectric tube of an ozone generator having ahead assembly with a side wall, a removable upper closure plate and alower seal plate, and a removable conductive contact plate disposedintermediate the upper closure plate and lower seal plate for formingupper and lower chambers therein, wherein the contact plate and lowerseal plate have a plurality of coaxially aligned apertures formedtherein for suspending a plurality of ozone generating cells, each ozonegenerating cell including removable suspension means, a hollowdielectric tube suspended from and extending through a respectiveremovable suspension means and removable with the removable suspensionmeans, and an electrode assembly suspended within the hollow interior ofits respective dielectric tube, the method comprising: removing theupper closure plate; removing the contact plate whereby each of theindividual electrode assemblies may be individually accessed; liftingthe individual electrode assembly having the dielectric tube to bereplaced from the dielectric tube; removing the removable suspensionmeans and its associated suspended dielectric tube from its respectivelower seal plate aperture; sliding a replacement dielectric tube intothe removed suspension means; sliding the removed suspension means andthe replacement dielectric tube into its respective lower seal plateaperture; sliding the lifted electrode assembly into the replaceddielectric tube; and sliding the electrode assembly with its replaceddielectric tube suspended from its associated suspension means back intoplace.
 8. The method of claim 7 wherein: each lower seal plate aperturecomprises threads and each removable suspension means comprises athreaded collar insert, and the removing the removable suspension meansand its associated suspended dielectric tube comprises connecting aturning device to engage the notches of the threaded collar insert andturning the threaded collar insert to disengage it from the threads ofits respective seal plate aperture.